The present invention concerns flashing formed of flexible synthetic material for installation on the inside and outside corners of a roof structure.
The application of sheets of synthetic plastic material to roofs is generally termed membrane roofing. Such roofing material is now becoming widely accepted for application to flat roofs for reasons of longevity and ease of application. Typically such roofing material is applied to horizontal flat roof structures of commercial buildings. Corners resulting from structures in place on a roof, as for example, air conditioning housings, skylights, exhaust ventilators, etc. are particularly difficult to seal. Intersections encountered in the application of roofing include inside and outside corners with sloped as well as perpendicularly related surfaces which are susceptible to being a cause of leaks.
In the prior art, U.S. Pat. No. 364,304 discloses flashing including cheese cloth panels on which a thick coating of cement or glue, is applied to provide flashing for metal roofing panels. Overlapped segments of flashing are disclosed
U.S. Pat. No. 5,675,939 discloses flashing having symmetrical halves intended for installation beneath the sloped roof and a vertical wall of a building.
U.S. Pat. Nos. 4,799,986 and 4,872,296 disclose pliable plastic flashing for corner installation on membrane roofing with the flashing slotted and having horizontal portions for heat welding to flat roof membrane and with vertical extensions joined by a flexible corner piece heat welded to surfaces of the horizontal portions. The flashing is for corners of roof mounted equipment having vertical wall surfaces.
U.S. Pat. No. 4,248,926 discloses sheet material for flashing use having a layer of knitted fabric material and adjacent layers of a rubber compound for flexure during installation.
U.S. Pat. No. 4,700,512 discloses flashing of the membrane type for installation on both inside and outside corners of foundations and roofs. The intersecting walls and roof surfaces being protected have perpendicular surfaces.
U.S. Pat. No. 5,706,610 discloses flashing having a slit extending from a central area to its perimeter wherein the flashing is comprised of two portions joined by heat welding with one of said portions adapted to seal the intersection of intersecting walls.